Method for design and control of properties of simulated food particles for process monitoring and validation of aseptically processed multiphase foods and biomaterials

ABSTRACT

This disclosure is directed to simulated food particles. In one possible configuration and by non-limiting example, the disclosure includes a method for design and control of properties of simulated food particles for process monitoring and validation of aseptically processed multiphase foods and biomaterials.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Application No. 62/086,683,titled METHOD FOR DESIGN AND CONTROL OF PROPERTIES OF SIMULATED FOODPARTICLES FOR PROCESS MONITORING AND VALIDATION OF ASEPTICALLY PROCESSEDMULTIPHASE FOODS AND BIOMATERIALS, the disclosure of which is herebyincorporated by reference in its entirety.

SUMMARY

In general terms this disclosure is directed to simulated foodparticles. In one possible configuration and by non-limiting example,the disclosure includes a method for design and control of properties ofsimulated food particles for process monitoring and validation ofaseptically processed multiphase foods and biomaterials.

One aspect is a method for construction and use of implant-carryingsimulated particles for validation of continuous flow thermal processesfor foods and/or biomaterials comprising: i) establishing a size andshape of a carrier particle; ii) establishing a size/volume of aninternal cavity needed to carry implants; iii) separating a particledesign into at least two components different in size and weight; iv)identifying and using at least one polymer less dense than water at roomtemperature, and at least one polymer with a higher density than waterat room temperature; v) fabricating each of the components from at leasttwo different polymers; vi) assembling constituent elements of theparticle design into a hermetically sealed assembly incorporating atleast one detectable or recoverable implant; vii) using the assembledparticles to generate a population of particles with a range of criticalproperties; viii) using the assembled population as a test set todetermine limits of residence times and lethalities accumulated by theprocessed products; and ix) identifying a fastest flowing configurationof the population and using the design to generate a larger populationof test particles to be used for process validation.

Another aspect is a test population/set of simulated particlesincorporating at least two different polymers with varying flow andthermal properties within a range established by the used polymers.

A further aspect is a method of determination of critical simulatedparticle property values (density) comprising the selection of amulti-polymer particle construction configuration with a shortest(fastest) residence time.

Yet another aspect is a method of process validation by implementing theparticle configuration design, determined by selection of amulti-polymer particle construction configuration with a shortest(fastest) residence time, as the implant carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates examples of composite particle components of anexample two-component carrier particle and examples of associatedimplants.

FIG. 2 illustrates an example of an assembled simulated sphericalparticle.

FIG. 3 illustrates another example of an assembled simulated sphericalparticle.

FIG. 4 is a graph providing a summary of measured residence times in ahold tube of a continuous flow sterilization installation for sphericalsimulated particles.

FIG. 5 is a graph providing another summary of measured residence timesin the hold tube of a continuous flow sterilization installation forspherical simulated particles.

FIG. 6 is a table showing individual weights and codes of simulatedparticles assembled using a selected combination of polymers whichyielded the lowest residence times when tested under full flowconditions in a continuous flow sterilization system.

FIG. 7 is a table showing individual weights and codes of simulatedparticles assembled using a selected combination of polymers whichyielded the second lowest residence time levels when tested under fullflow conditions in a continuous flow sterilization system.

FIG. 8 is a graph illustrating an example of a cumulative residence timedistribution.

FIG. 9 is a graph illustrating an example of another cumulativeresidence time distribution.

DETAILED DESCRIPTION

Various embodiments will be described in detail with reference to thedrawings, wherein like reference numerals represent like parts andassemblies throughout the several views. Reference to variousembodiments does not limit the scope of the claims attached hereto.Additionally, any examples set forth in this specification are notintended to be limiting and merely set forth some of the many possibleembodiments for the appended claims.

Simulated/fabricated food particles are used to design, establish andvalidate the pasteurization, sterilization processes performed undercontinuous flow conditions followed by aseptic packaging. They primarilyserve as carriers and containers for detectable and/or quantifiableimplants which serve to characterize the time-temperature history thatthe particles are subjected to during processing as well the cumulativelethality received in order to characterize and quantify the efficiencyand safety of the implemented processes and achieved sterility levels.

These particles usually carry two types of implants—the first type isused to monitor the flow of the particles through the processing systemand is typically magnetic. The second type is typically thermo-sensitiveand is used to quantify the time-temperature history of the process(cumulative lethality) and can be physical (e.g. eutectic alloy orferromagnetic shield based thermomagnetic switches), chemical (e.g. aknown concentration of a solution or suspension of a chemical substancewith known kinetics of thermal degradation and a straightforward meansof post-process quantitative analysis), enzymatic (e.g. ahyper-thermophillic/extremophylic enzyme solution or suspension with aknown initial concentration and kinetics of thermal degradation and aconvenient method of analysis) and biological (e.g. thermo-resistantbacterial spores, typically non-toxic but more resistant surrogates forspores of proteolytic Clostridium botulinum, such as spores ofGeobacillus stearothermophillus, Clostridium sporogenes or Bacillussubtilis.

It is important to make sure that these fabricated implant carrierparticles have appropriate, i.e. conservative flow and thermalinsulating properties. These properties need to be selected or adjustedto achieve the conservative design characteristics. For example, thethermo-sensitive implants carried by the fabricated particles need to bedesigned so that they get exposed to the minimal possible thermaltreatment. In other words, each fabricated particles needs to flow atleast as fast as the fastest food particle contained in the product andit also needs to provide at least the same level of thermalinsulation/protection to implants carried within its cavity as the mostinsulating food particle provides to its geometric center. Therefore, ifthe fabricated particles have been designed correctly, achieving theappropriate sterility level (the cumulative lethality level) for thethermosensitive implants will guarantee that all other particulateproduct components and ingredients have been properly sterilized,therefore proving the safety of the delivered thermal process.

Flow characteristics of these particles are determined by their size,geometry, surface characteristics and density as well as carrier fluidcharacteristics, temperature levels experienced through the process andgeometry of the flow-through continuous flow processing system.

Since a majority of these characteristics are either pre-determined,impossible to control or constant, effective particle density is themost significant controllable variable for these particles and can beused to control of flow properties of fabricated particles carried bythe product carrier fluid while surrounded by real food particle loads.

Effective thermal insulation (protection) characteristics of fabricatedparticles are determined by material (polymer) density, heat capacity(specific heat), thermal conductivity and wall thickness of the materialbetween the external surface and the surface surrounding the internalparticle cavity.

One possible technique used to control the thermal insulationcharacteristics is the selection of the material of fabrication as wellas addition or subtraction of the implemented material wall thickness.

Another method for control of flow and thermal properties according tothe present disclosure involves the use of two or more different polymermaterials to assemble the particles. Each of the used polymers hasdifferent thermo-physical characteristics like density, coefficient ofthermal expansion, thermal conductivity, heat capacity etc. and by usingdifferent combinations of polymer materials, a range of these propertiescan be implemented for testing and enable the assembly of a populationof particle which cover the entire range of flow and thermal propertiesexpected to occur within the aseptic processing system for a certainprocessed product or product range.

In some embodiments the method according to the present disclosure makesit possible to generate this test population without the tedious andtime-consuming adjustments and measurements when using different wallthicknesses of the material (which can also be very expensive, due tothe high cost of fabrication of individual injection molds) for controlof thermal insulation (implant protection) properties, and theassociated method of ballast implanting for control of effective densityof fabricated and assembled particles which can be done by implantingminiature glass beads into the hollow carrier cavity before assembly.This ballast loading can be used to control the effective density ofassembled particles and thereby control their flow properties, i.e.residence times within the processing system.

Some embodiments of a method according to the present disclosure includeone or more of the following advantages:

I. The ability to maintain the internal carrier cavity of the particlesassembled using different polymers in identical size and shape. Thisenables the use of identical flow monitoring and thermo-sensitiveimplants into the cavity for the whole range of generated particleproperties. This enables the testing, monitoring and objectivecomparisons of residence times and accumulated thermal lethality rates(microbial spore inactivation rates) better than when the internalcavity of the assembled particles varies due to the varying wallthicknesses surrounding the cavity (the external geometry and dimensionsof the simulated particles need to remain identical for a specificpopulation simulating a specific ingredient) and weight/ballast loadswithin the cavity.

II. The ability to quickly and simply assemble large test populations ofparticles with a wide range of recording and/or real time orpost-process detectable and identifiable implants and tags with a widerange of flow and thermal properties as well as large populations ofnarrowly focused property ranges—the first population can be used intesting and establishment of critical carrier properties (fastestflowing, slowest heating) required for subsequent testing and validationwhile the narrowly focused property population can be used for actualresidence time and thermal sterilization and validation, preferablyutilizing both types of implants discussed previously within eachparticle's cavity.

In some embodiments simulated particles are assembled and tested usingcombinations of several different polymers. Since the simulatedparticles are asymmetric and made out of 2 or 3 components—the bottomand the lid are different in the case of a 2 component particle andbottom, lid and interconnecting tube segment can be made from differentpolymers in the case of a 3 component particle, therefore someembodiments enable the construction of the following number of differentconfigurations (different flow and heat penetration properties) ofsimulated particles, as shown in Table 1.

TABLE 1 Number of Number of different Number of different differentconfigurations for a configurations for a polymers used for 2-component3-component construction particle assembly particle assembly 2 4 8 3 927 4 16 64 5 25 125

FIG. 1 depicts examples of composite particle components of atwo-component carrier particle and associated implants. Thisillustration is intended to provide just one of the numerous possibleembodiments, i.e. any particle assembly with asymmetrical (different ortwo different sizes designed to assemble into a spherical, cubic,parallelepiped , cylindrical, ovoid, bean-shaped etc.) top and bottomparts can also be used in other embodiments. For example, the top andbottom parts can be assembled to provide the set of key properties basedon one or the other used polymer as well as two additional intermediateconfigurations where one is closer to Polymer A when it is used tofabricate the bottom component and the other closer to Polymer B.

Using the outlined concept of particle assembly using combinations ofdifferent polymers for bottom and top components the followingconfigurations have been assembled in 10 mm (Table 2) diameter and 0.75inch diameter (Table 3) formats. The measured weights in grams of bothformats with 16 different configurations and 3 replicates of eachconfiguration are presented in Table 2 (10 mm diameter) and Table 3(0.75 inch).

TABLE 2 Weights of 10 millimeter diameter composite spherical particleswith different polymer combinations using 4 polymers (3 replicateparticles for each polymer combination) TOP BOTTOM TPX PolyPropPolySulfone Ultem WEIGHT GRAMS (DOT/Replicate A) TPX 0.843 0.848 1.050.953 PolyProp 0.839 0.846 0.92 0.96 PolySulfone 0.96 1.064 1.14 1.168Ultem 1.064 1.072 1.159 1.197 WEIGHT GRAMS (CIRCLE/Replicate B) TPX0.827 0.841 0.938 0.957 PolyProp 0.843 0.831 0.96 0.956 PolySulfone1.054 1.051 1.15 1.188 Ultem 1.065 1.074 1.195 1.182 WEIGHT GRAMS(CROSS/Replicate C) TPX 0.849 0.845 0.936 0.942 PolyProp 0.821 0.8340.94 0.959 PolySulfone 1.062 1.054 1.152 1.152 Ultem 1.072 1.092 1.1671.191

TABLE 3 Weights of 0.75 inch diameter composite spherical particles withdifferent polymer combinations using 4 polymers (3 replicate particlesfor each polymer combination) TOP BOTTOM TPX PolyProp PolySulfone UltemWEIGHT GRAMS (DOT/Replicate A) TPX 1.513 1.528 1.765 1.753 PolyProp1.527 1.557 1.78 1.785 PolySulfone 1.985 2 2.215 2.218 Ultem 2.027 2.0422.273 2.26 WEIGHT GRAMS (CIRCLE/Replicate B) TPX 1.512 1.571 1.734 1.764PolyProp 1.547 1.557 1.754 1.761 PolySulfone 2.016 1.992 2.219 2.226Ultem 2.068 2.056 2.27 2.283 WEIGHT GRAMS (CROSS/Replicate C) TPX 1.5221.53 1.72 1.766 PolyProp 1.575 1.59 1.745 1.806 PolySulfone 1.984 2.032.202 2.232 Ultem 2.49 2.064 2.25 2.254

FIGS. 2 and 3 show examples of the assembled particle populations andthe numeric codes for each of the 16 configurations in both formats.

FIG. 2 illustrates an example of fully assembled simulated sphericalparticle. In some embodiments the simulated spherical particle is a 10mm simulated spherical particle (such as illustrated in FIG. 1), withfour (Polypropylene/PP, Polymethylpentene/TPX, Poilysulfone/PS andUltem/ULT) used polymers and weights specified in Table 2. Otherembodiments include other sizes and configurations.

FIG. 3 illustrates an example of fully assembled simulated sphericalparticle. In some embodiments the simulated spherical particle is a 10mm spherical simulated particle (such as illustrated in FIG. 1), withfour (Polypropylene/PP, Polymethylpentene/TPX, Polysulfone/PS andUltem/ULT) used polymers and weights specified in Table 2 and associatedcodes. Other embodiments have other sizes and configurations.

FIG. 4 is a graph providing a summary of measured residence times in thehold tube of a continuous flow sterilization installation for 10 mmspherical simulated particles illustrated in FIG. 1 with four(Polypropylene/PP, Polymethylpentene/TPX, Polysulfone/PS and Ultem/ULT)used polymers and weights specified in Table 2 and codes as shown inFIG. 3. The example shown in FIG. 4 involves an operating temperaturerange that is at ambient/room temperature, and the carrier material andproduct is CMS suspension in water with 12% corn particles.

FIG. 5 is a graph providing a summary of measured residence times in thehold tube of a continuous flow sterilization installation for 10 mmspherical simulated particles illustrated in FIG. 1 with four(Polypropylene/PP, Polymethylpentene/TPX, Polysulfone/PS and Ultem/ULT)used polymers and weights specified in Table 2 and Codes as shown inFIG. 3. Configurations #9, #14, #15 and #16 have been omitted from thetest population based on the previously measured long residence times(slow movement). In this example the operating temperature range is fullthermal sterilization and the carrier material and product is tomatovegetable soup with 10% corn particles.

FIGS. 4 and 5 illustrate the importance of an appropriate densityadjustment for carrier particles.

Specifically, as illustrated by the graphs some particle configurationscould be up to 50% faster than others. This means that if slowerparticles are used as implant carriers for safety validation, thecumulative lethality received by the particulate phase could be verysignificantly overestimated, which could lead to an unsafe processvalidation and ultimately and unsafe product which could eventually posea significant health hazard for the consuming public.

This is particularly important when considering the new possibilities ofincluding the novel implants into the particle cavities, or even intoreal food particles like RFID tags and RFID technology based temperaturerecording and/or signaling devices.

These devices are to a large extent based on metallic components andtherefore add a significant level of effective density to any carrier orreal food or biomaterial particle—this would likely result in asignificant particle flow slow down—and therefor extended residencetimes in both heating and holding segments of the sterilizationinstallations.

Ultimately, this results in over-processing and a falsely high level oflethality received by such devices.

Therefore it is important to establish the particle configuration whichprovides the conservative (fast moving) flow/residence timecharacteristics to the implant-carrying assemblies.

FIGS. 4 and 5 also illustrate the importance and utility of at leastsome embodiments according to the present disclosure which provides amethod and procedure for production of the test particle population witha range of critical properties as well as a method for comparisons oftheir residence times and received lethality levels in each processsegment.

Subsequent to the residence time trials using the 16 multi-polymerconfigurations, two configurations resulting in the fastest particles(shortest residence times) have been replicated for 100 particles eachwith the resulting particle weights shown in FIGS. 6 and 7.

FIG. 6 is a table showing individual weights and codes of simulatedparticles assembled using a selected combination of two polymers whichyielded the lowest residence times when tested under full flowconditions in a continuous flow sterilization system. FIG. 6 shows aconfiguration A and data in grams.

FIG. 7 is a table showing individual weights and codes of simulatedparticles assembled using a selected combination of two polymers whichyielded the second lowest residence time levels when tested under fullflow conditions in a continuous flow sterilization system. FIG. 7 showsa configuration B and data in grams.

Multiple particle replicates from the two selected configurations havebeen subsequently subjected to residence time testing underrepresentative processing conditions (real product, full representativesterilization treatment using microwave heating and time of exposure,flow rate, temperatures and pressures).

FIG. 8 is a graph illustrating an example of a cumulative (whole holdtube) residence time distribution for configuration A.

FIG. 9 is a graph illustrating an example of a cumulative residence timedistribution for configuration B.

FIGS. 8 and 9 illustrate that, in at least some embodiments, very narrowresidence time distributions can be generated and achieved by selectinga proper particle configuration and maintaining a narrow range ofeffective particle densities.

Accordingly, and as discussed herein, some embodiments are or includeaseptically processed and packaged particulate foods and biomaterialsfor residence time measurements and safety validation/biovalidation.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the claimsattached hereto. Those skilled in the art will readily recognize variousmodifications and changes that may be made without following the exampleembodiments and applications illustrated and described herein, andwithout departing from the true spirit and scope of the followingclaims.

What is claimed is:
 1. A method for construction and use ofimplant-carrying simulated particles for validation of continuous flowthermal processes for biomaterials comprising: i) establishing a sizeand shape of a carrier particle; ii) establishing a size or volume of aninternal cavity needed to carry implants; iii) separating a particledesign into at least two components different in size and weight; iv)identifying and using at least one polymer less dense than water at roomtemperature, and at least one polymer with a higher density than waterat room temperature; v) fabricating each of the components from at leasttwo different polymers; vi) assembling constituent elements of theparticle design into a hermetically sealed assembly incorporating atleast one detectable or recoverable implant; vii) using the assembledparticles to generate a population of particles with a range of criticalproperties; viii) using the assembled population as a test set todetermine limits of residence times and lethalities accumulated by theprocessed products; and ix) identifying a fastest flowing configurationof the population and using the design to generate a larger populationof test particles to be used for process validation.
 2. The method ofclaim 1, wherein the biomaterials comprise food.
 3. A set of simulatedparticles incorporating at least two different polymers with varyingflow and thermal properties within a range established by the usedpolymers.
 4. A method of determination of critical simulated particleproperty values comprising: selecting a multi-polymer particleconstruction configuration with a shortest residence time.
 5. The methodof claim 4, wherein the multi-polymer particle constructionconfiguration with the shortest residence time is the fastestmulti-polymer particle construction configuration.
 6. The method ofclaim 4, wherein the particle property values are the density of theparticles.
 7. A method of process validation comprising implementing theparticle configuration design determined as specified in claim 4 as animplant carrier.